Les phosphates de cuivre de type NASICON CuxM2(PO4)3 (x=0,5 pour Cu2+; x=1 pour Cu+) (M=Ti, Zr) sont des matériaux remarquables par leurs propriétés catalytiques et luminescentes. L'établissement de modèles rendant compte de ces propriétés à nécessité la localisation du cuivre et la connaissance précise de son environnement par diverses techniques complémentaires : EXAFS, diffraction de neutrons, RMN, microscopie électronique. Le caractère lacunaire de ces phosphates a permis l' enrichissement en cuivre de ces matériaux et l'intercalation notamment du lithium et de l'hydrogène au sein de ces phases.

Ce travail concerne la synthèse et l'étude de nanoparticules d'oxydes de terres rares. Les agrégats sont synthétisés par LECBD (Low Energy Cluster Beam Deposition) puis déposés sur différents substrats pour analyse. La spectroscopie de photoélectrons X montre que les agrégats produits possèdent la stoechiométrie du matériau massif. Les dépôts sont imagés par microscopie électronique. Dans les conditions usuelles les agrégats déposés ont une taille faiblement dispersée autour d'une valeur moyenne de 3 nm. Les agrégats sont alors cristallisés et présentent une forme particulière, le dodécaèdre rhombique. La conservation de la structure cristalline ainsi que la stabilité particulière du dodécaèdre rhombique sont discutées en relation avec les propriétés de la liaison ionique. Les propriétés de luminescence de Gd2O3 dopé Eu3+ ont permis de mettre en évidence une transition de structure pour les agrégats de très petite taille. Cette transition peut être expliquée par la pression de Gibbs induite par la tension de surface. La simulation de la luminescence des agrégats montre l'influence importante de la surface dans l'élargissement inhomogène des spectres de luminescence des nanoparticules. Le confinement quantique dans Gd2O3 dopé Eu3+ est démontré. Le comportement observé présente des similitudes avec celui de matériaux moins ioniques. Une interprétation est proposée.

comme luminophore rouge dans les nouveaux dispositifs de visualisation à panneaux plasma ; le borate Li6(Y,Gd)(BO3)3: Ce3+ est particulièrement approprié pour la détection des neutrons. Outre les borates Li6Ln(BO3)3 (Ln = terre rare) et Li3Ln2(BO3)3 antérieurement connus, l'étude des diagrammes ternaires Li2O-B2O3-Ln2O3 a mis en évidence l'existence de quatre autres compositions : les borates Li3Ln(BO3)2 et les oxyborates LiLn6O5(BO3)3, LiLn2O2BO3 et<br />Li2Ln5O4(BO3)3. Chacune des structures a été résolue sur monocristal par diffraction des rayons X.<br />Une caractéristique des oxyborates est l'existence d'un assemblage de tétraèdres OLn4, tridimensionnel<br />dans les borates LiLn6O5(BO3)3 , bidimensionnel dans les phases Li2Ln5O4(BO3)3 et LiLn2O2BO3 , les groupes (BO3)3- et les ions Li+ se disposent dans des cavités ou entre les couches de ces sous-réseaux. Une étude de la luminescence des ions Eu3+, Tm3+ et Ce3+ a été effectuée afin notamment d'évaluer les performances de ces nouveaux matériaux en tant que luminophores ou scintillateurs. Pour la première fois dans des composés du bore, une luminescence de transfert de charge du lanthane et du cérium tétravalent a par ailleurs été observée.

Ce travail présente la préparation et la caractérisation de matériaux hybrides organiques<br />inorganiques pour applications en la photonique. La théorie associée à la préparation des<br />matériaux est décrite et quelques résultats d'autres travaux déjà publiés concernant ces<br />matériaux sont présentés. La structure du matériau obtenu après hydrolyse et condensation est<br />détaillée en présence de différentes quantités de zirconium. Les analyses de rayons X mettent<br />en évidence les particules qui formant ce matériau et l'influence du zirconium sur la forme de<br />cette particule. La spectroscopie dans la région de l'infrarouge a permis l'étude des liaisons<br />caractéristiques du matériau et les modifications structurelles liées à l'ajout de la phase<br />inorganique. Les caractéristiques du matériau ont été analysées par résonance magnétique<br />nucléaire. Les caractéristiques spectroscopiques du matériau sont détaillées, notamment la<br />luminescence intrinsèque du matériau et l'influence du zirconium. On montre que<br />l'introduction de l'ion europium confère de nouvelles propriétés et permet aussi une évaluation<br />structurelle complémentaire du matériau. Diverses applications du matériau étudié sous la<br />forme de couches minces sont présentées. Nous avons obtenu des réseaux de diffraction par<br />holographie, par lithographie, et également un effet laser à contre-réaction répartie dans des<br />films dopés avec la rhodamine 6G.

Reproduction de : Thèse de doctorat : Lasers, molécules, rayonnement atmosphérique : Lille 1 : 2004. / Résumé. Titre provenant de la page de titre du document numérisé. Trois articles en anglais retirés. Bibliogr. p. 185-190.

Atherosclerosis and specifically rupture of vulnerable plaques account for 23% of all deaths worldwide, far surpassing both infectious diseases and cancer. Plaque-based macrophages, often associated with lipid deposits, contribute to atherogenesis from initiation through progression, plaque rupture and ultimately, thrombosis. Therefore, the macrophage is an important early cellular marker related to vulnerability of atherosclerotic plaques. The objective of my research is to assess the ability of multiple optical imaging modalities to detect, and further characterize the distribution of macrophages (having taken up plasmonic gold nanoparticles as a contrast agent) and lipid deposits in atherosclerotic plaques. Tissue phantoms and macrophage cell cultures were used to investigate the capability of nanorose as an imaging contrast agent to target macrophages. Ex vivo aorta segments from a rabbit model of atherosclerosis after intravenous nanorose injection were imaged by optical coherence tomography (OCT), photothermal imaging (PTW) and two-photon luminescence microscopy (TPLM), respectively. OCT images depicted detailed surface structure of atherosclerotic plaques. PTW images identified nanorose-loaded macrophages (confirmed by co-registration of a TPLM image and corresponding RAM-11 stain on a histological section) associated with lipid deposits at multiple depths. TPLM images showed three-dimensional distribution of nanorose-loaded macrophages with a high spatial resolution. Imaging results suggest that superficial nanorose-loaded macrophages are distributed at shoulders on the upstream side of atherosclerotic plaques at the edges of lipid deposits. Combination of OCT with PTW or TPLM can simultaneously reveal plaque structure and composition, permitting assessment of plaque vulnerability during cardiovascular interventions. / text

published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy

published_or_final_version / Applied Geosciences / Master / Master of Science

Tian Shan is one of the most important orogenic belts in central Asia. It has been reactivated as a result of the Cenozoic India-Eurasia collision. Dating of the late Cenozoic tectonic deformation of Tian Shan and its piedmonts is important for understanding the mountain building as well as evaluating seismic hazards in the region. This study is focused on the applications of optical dating to the late Quaternary uplift and thrust activity along Manas River, in the northern piedmont of the Tian Shan, China. The sediments on river terraces were dated with optical dating. The elevations were measured with the kinematic global position system (GPS). The results suggest that two phases can be identified according to the significantly different river incision rates. One phase was from ~20 ka to ~4.8 ka, with a much slower incision rate of ~ 2.2 ± 0.6 mm/yr. The other phase was from ~4.8 ka to present, with a faster incision rate of ~ 13.5 ± 0.6 mm/yr. The accelerated incision rate of Manas River was mainly attributed to the tectonic forces, suggesting that the tectonic uplift was significantly intensified since ~4.8 ka in the northern piedmont of Tian Shan. The study region has suffered from multiple thrust activities during the late Quaternary, which led to the intensive deformations of the river terraces. By studying the deformed terraces, I evaluated the timing of the past thrust activities as well as the vertical slip rate of the thrust faults. The results demonstrated that the thrust activity intensified during the late Holocene, as manifested by the more frequent thrust activities and higher vertical slip rates. Both quartz and potassium feldspar can be as dosimeters for optical dating of sediments. However, quartz OSL is sometimes seriously impeded with problems such as very dim signals and insufficient bleaching problems. K-feldspar has attractive advantages over quartz, despite of problem of anomalous fading. K-feldspar was explored in this study, by investigating the relationship between the infrared stimulated luminescence (IRSL) and blue light stimulated luminescence (BLSL) signals. For IRSL and BLSL at 60 °C, it was suggested that most of the IRSL could be bleached by blue light (BL), while the BLSL could only be partially bleached by infrared (IR) stimulation. Besides, the fast and medium components of BLSL were mainly associated with the IRSL. If IR stimulation temperature was raised from 60 to 200 °C, at least two portions of the IRSL signals at 200 °C were observed. One portion could be bleached by BL at 60 °C and the other portion was hardly bleached by BL at 60 °C. Dating of K-feldspar from the various signals provided cross-checking for the reliability of quartz OSL for dating sedimentary samples. / published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy

New applications of the optically stimulated luminescence (OSL) dating were carried out with the aim of understanding late Quaternary activities for the Tibetan Plateau. This included studying the slip rate of the Altyn Tagh Fault, northeast Tibetan Plateau, and revealing the environmental changes derived from large inland lake’s evolution, central south Tibet. Two deflected streams across the Altyn Tagh Fault close to Aksay (39°24.572’N, 94°16.012’E) were investigated. Geomorphological analysis suggests that loess covering deflected stream banks has recorded past faulting events. A conceptual model is proposed illustrating the relationship. OSL dating of sixteen loess samples at both streams support the model, suggesting the loess is deposited episodically after fault strikes and subsequent channel wall refreshment. The age and offset indicate a slip rate of 11 ±2 mm/yr for this part of the Altyn Tagh Fault. Another river section near Aksay was also investigated for the slip rate information. Two risers between three terraces are clearly offset; OSL dating of loess covering terrace surfaces yielded terrace ages. Using the upper-terrace age to represent riser displacement duration, the rate is estimated to be 12 ±1 mm/yr. The result suggests that using upper terrace is more suitable in this region. Notably, though, the slow rate is at odds with proposals that assume high-speed extrusion (~23 mm/year) of the Tibetan Plateau being accommodated by the Altyn Tagh Fault. Palaeo-shorelines around the third largest lake in Tibet, Zhari Namco, were for the first time systematically investigated using OSL dating. Twenty-two sediment samples from eleven shorelines indicate that the water level has dropped ~128 m and the lake has undergone stepwise shrinkage since 8.2 ka. Digital elevation model calculation indicates the lake has shrunk from 4605 km2 in size at 8.2 ka to 996 km2 at present, which is equivalent to ~300 km3 of water. This implies a significant reduction in precipitation over the past 8.2 ka, a result of weakening Indian Monsoon or a shift of monsoon circulation path. The result is consistent with other lake-core, ice-core climate proxies and solar insolation changes, implying the dominance of a weakening Indian Monsoon over central Tibet in the Holocene. Using the elevation of the highest shoreline of the four largest lakes in Tibet, the early Holocene Pan-lake hypothesis is proposed for the central Tibet. In addition to these applications of OSL dating, technical studies on sensitivity changes and residual doses have been carried out for potassium rich feldspar (K-feldspar). Recent development of infrared stimulated luminescence (IRSL) signals from K-feldspar has shown great potential for extending the datable range for OSL dating. Sensitivity changes and residual doses of post-IR IRSL and multi-elevated -temperature post-IR IRSL protocols for K-feldspar were studied. A sensitivity decrease is observed after adopting a high temperature IRSL. IRSL signals stimulated at high temperature are found to contain large residual doses. The residual dose rises with stimulation time, suggesting that the initial part of IRSL signals contains more easy-to-bleach signals comparing with the later part. / published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy